Copper-binding protein (Intracellular)

Intracellular copper-binding proteins, such as metallothioneins and copper chaperones (e.g., ATOX1, CCS), are essential for sequestering and transporting copper ions within the cell to prevent toxicity and ensure proper enzyme function (UniProt, 2024). These proteins are particularly significant in oncology due to their role in the trapping mechanism of copper-based hypoxia-selective agents like Cu-ATSM (Fujibayashi et al., 1997). In the low-oxygen environment of hypoxic tumor cells, copper(II) complexes undergo bioreduction to copper(I), causing the copper ion to dissociate from its ligand and bind tightly to the thiol groups of these intracellular proteins (Dearling et al., 2002). This selective accumulation allows these proteins to act as a reservoir for diagnostic radionuclides or therapeutic agents, facilitating the visualization of aggressive tumor regions (Xiao et al., 2023). Tumor hypoxia is a critical factor in radiation resistance, making this trapping mechanism a valuable tool for identifying and potentially treating resistant disease. Beyond imaging, these proteins are involved in tumor angiogenesis and proliferation, making the copper-binding pool a target for therapeutic intervention (PubChem, 2024).

Other names

MetallothioneinsCopper chaperonesThiol-containing intracellular proteinsIntracellular copper-binding pool

Redox-mediated intracellular trapping: Reduction of Cu(II) to Cu(I) in hypoxic environments leads to ligand dissociation and subsequent binding of the copper ion to intracellular thiol-rich proteins.